How to cancel withContext in kotlin-CodePudding

I have one function inside that I am trigger an event at particular time.

fun startTimeWarning() {
     viewModelScope.launch {
        withContext(Dispatchers.Default) {
            if (!isActive) {
                delay(2000)
                // trigger event
            }
        }
     }
}

Now I want to trigger new event in cancelTimeWarning and make sure startTimeWarning is not active. Is it possible to cancel in withContext?

fun cancelTimeWarning() {
     viewModelScope.launch {
           // new event trigger
     }
}

I checked in this answer but I don't think this will help me. Many thanks

CodePudding user response：

It's not that you want to use Job or not. The viewModelScope.launch will return a Coroutine Job, so that you can use this reference to cancel it manually in your case.

private var timeWarningJob: Job? = null
...
fun startTimeWarning() {
     timeWarningJob = viewModelScope.launch {
        withContext(Dispatchers.Default) {
            if (!isActive) {
                delay(2000)
                // trigger event
            }
        }
     }
}

fun cancelTimeWarning() {
    timeWarningJob?.cancel() // Cancel your last job
    viewModelScope.launch {
          // new event trigger
    }
}

Edited:

If your supervisor forbid you from using Job, you can define your own context and cancel it later just like above.

private val timeWarningContext:CoroutineContext = Dispathers.Default
...
fun startTimeWarning() {
     viewModelScope.launch {
        withContext(timeWarningContext) {
            if (!isActive) {
                delay(2000)
                // trigger event
            }
        }
     }
}

fun cancelTimeWarning() {
    timeWarningContext.cancel() // Cancel your last job
    viewModelScope.launch {
          // new event trigger
    }
}